1. Field of the Invention
The present invention relates to a switching control circuit.
2. Description of the Related Art
A common switching power supply circuit includes an overcurrent protecting circuit configured to prevent a current, which is greater than or equal to a predetermined current, from passing through a power transistor configured to drive a load. For example, a pulse-by-pulse-method overcurrent protecting circuit is known as the overcurrent protecting circuit, that is configured to detect whether the current passing through the power transistor is greater than or equal to the predetermined current, that is, whether the current is an overcurrent for each switching cycle, and turn off the power transistor when the current is an overcurrent, (see, e.g., Japanese Laid-Open Patent Publication No. 2009-261100).
When the load is short-circuited in a switching power supply circuit that employs the pulse-by-pulse-method overcurrent protecting circuit, an overcurrent passes through the power transistor in every switching cycle. Therefore, if the short circuit of the load is continued for a long time, the power transistor, etc., may be broken.